Case IH 1044-03 - UCM – UCM: UCM: Electro-hydraulic backup pump pressure sensor voltage high

A "voltage high" designation on a hydraulic pressure sensor indicates that the control module is receiving a signal voltage that exceeds the maximum expected threshold (typically near or at 5.0 Volts). In Case IH 5-volt reference systems, this is most commonly caused by an open circuit (such as a disconnected sensor, a broken signal wire, or a missing ground) or a short to a higher voltage source.

• MAGNUM AFS Connect
• Axial-Flow Combines
• Magnum Series Tractors
• Puma Series Tractors
• Steiger Series 4WD Tractors
• Early Riser 2000 Series Planters

1. 1

   Verify if the code is Pending (intermittent wiring noise), Active (currently disabling hydraulics), or Permanent

2. 2

   Inspect the electro-hydraulic backup pump pressure sensor connector for moisture, corrosion, or poor terminal contact

3. 3

   With the ignition ON, backprobe the sensor connector to verify the UCM is sending the correct reference voltage (expected result is 5.0 ± 0.20 VDC)

4. 4

   Verify that the sensor has a solid ground (a missing ground will push the circuit voltage high)

5. 5

   Inspect the wiring harness between the UCM and the sensor for chafing, broken wires, or a short to battery power

1. 1

   Disconnect Power

   Always disconnect the negative battery terminal before repairing electrical sensors or wiring on the transmission/hydraulic systems.

2. 2

   Repair Wiring

   If the diagnostic checks revealed a chafed wire shorting to power or a broken wire creating an open circuit, cut the damaged section, solder a new wire, and seal it thoroughly with heat-shrink tubing.

3. 3

   Replace the Sensor

   If the wiring harness, 5V reference, and ground all test within specification, the internal circuitry of the pressure sensor has failed. Remove the faulty electro-hydraulic backup pump pressure sensor and install the replacement.

4. 4

   Reassemble and Clear Codes

   Reconnect the battery. Use a diagnostic scan tool to clear the active/stored fault codes from the UCM, or perform a cycle test to allow the module to verify the repair.